1. Field of the Invention
The present invention relates to a process for producing food proteins of fungal origin or from multicellular organisms, in particular by the application of a novel multicellular organism. It relates also to the food proteins thus obtained. The invention also concerns a fermentation apparatus which is especially suitable for the application of the process according to the invention. Also it relates to a process for the mutation of micro-organisms and in particular of fungi.
2. Description of the Prior Art
Micro-organisms (bacteria, yeasts, fungi) play a part in the preparation of human and animal foodstuffs by acting through their enzymes and they are used for industrial production of organic molecules, of which many are common metabolites (ethanol, acetic acid, citric acid, glycerol, lysine, glutamic acid, ascorbic acid, etc.).
From the beginning of the era of Pasteur, commensal micro-organisms have been cultivated on various substrates (molasses, bagasse, lactoserum, bisulfite liqours, etc.) in order to enrich the byproducts and to product biomasses. The biomasses were especially utilized in animal foods as vitamin, mineral salt and protein supplements.
For conjunctural reasons, the development of these practices has long remained limited. The causes of this stagnation have been: irregularity in quality, difficulty in mastering the cultivation and maintenance of strains, appearance of cheaper sources of proteins and vitamins, industrial restructurization, following the discovery of fossil resources, which has accelerated agricultural development, etc.
In the last twenty years, industrial production of biomasses has experienced a very distinct revival. The elements which have simulated this return are principally: the progress of molecular biology, the discovery of micro-organisms consuming unconventional energy sources (for example paraffins), the need for the resorption of agroalimentary effluents in larger and larger volumes, growing needs for proteins, the appearance of new technologies attempting to reduce energy consumption, etc.
Intense research into the cultivation of biomasses has developed since 1960. It has borne on alkane yeasts, bacteria oxidizing methanol, spirulines growing on carbonated media, mushrooms capable of metabolizing various types of effluents.
Nutritional tests carried out on numerous animal species have established the high nutritional value and inocuousness of biomasses thus obtained.
Micro-organisms capable of producing alimentary proteins are the bacteria and the fungi (yeasts and filamentous fungi); they must possess the following characteristics:
good specificity relative to the substrates, PA1 short doubling time (20 min. to 5 hours); PA1 high energy efficiency (100 g of carbohydrates=25 to 32 g of proteins); PA1 growth at required temperatures (from 20.degree. C. to 50.degree. C.); PA1 growth at extreme pH's, PA1 growth at low or high concentrations of substrates, PA1 they must effect maximum exhaustion of the media (reduction of the C O D and of the B O D from 90 to 98%), PA1 collecting and drying of the biomasse must be easy, PA1 the protein content must be high (40-65%) PA1 the nucleic acids and cellular wall contents must be low, PA1 the germs used must not possess pathogenic ability (virulence and excretion of toxins) and they must not produce bacteriocins, nor release unpleasant flavors, PA1 the protein efficiency coefficient (P.E.C.) of the biomass must be high.
It has been found, for the first time to the knowledge of applicant, that a filamentous micro-organism could serve as a food.
Indeed, although the bacteria and the filamentous fungi are currently used in food technology and for the production of various metabolites, of vitamins, of aminoacids, of antibiotics, enzymes, etc., only the yeasts have been sufficiently widely cultivated to be consumed as foods. This capacity of yeasts to provide large amounts of biomasses is confirmed with the discovery of their property of growth on alkanes. Numerous works, reviews and treatises have been published on the production of the nutritional qualities of yeast-foods.
The filamentous micro-organism used in the process of the invention belongs to the Trichoderma genus.
It has been found also that such a filamentous micro-organism enables the value of certain protein substrates to be enhanced, notably protein substrates with a high protein content whose utilization is limited due to the fact that they contain for example toxic materials and/or materials giving them a certain bitterness.
The process according to the invention hence enables the production of food proteins arising from the action of this filamentous micro-organism on protein substrates. The invention relates also to the protein products thus obtained, these products being constituted by proteins of modified (purified, detoxified or bitterness-free) substrates possibly in admixture with proteins of filamentous micro-organism or solely proteins of filamentous micro-organisms.
The process for the production of food proteins comprises the steps of cultivating, under conditions which will be defined below, a polyphage filamentous micro-organism capable of metabolizing notably agricultural products and rejects of food industries or to purify, detoxify and eliminate the bitterness of protein substrates.